Double wall liquid storage tank with sealing gasket and compression fitting

ABSTRACT

A dual tank assembly is provided for storing agricultural and industrial liquids. The assembly includes an outer tank and an inner tank nested within the outer tank. The outer tank has an upper shelf and the inner tank has a rim overlying the shelf with a leaf gasket therebetween to seal the space between the shelf and the rim. The outer tank includes a recessed flat wall adjacent the bottom of the tank to mate with a flat wall in the inner tank. A compression fitting is tightened to sandwich a gasket between the flat wall portions of the inner and outer tanks. A drain fitting extends through the flat portions of the tank for draining liquid from the inner tank. A separate drain plug is provided for draining liquid from the outer tank.

FIELD OF THE INVENTION

The present invention is directed towards a liquid storage tank for agricultural and industrial chemicals, having dual nested tanks with a sealing gasket and a compression fitting.

BACKGROUND OF THE INVENTION

Various types of liquid storage tanks for agricultural and industrial chemicals are well known, and typically range in size from approximately 50 gallons to over 10,000 gallons. Some of these tanks have double walls to capture and leakage from the inner tank and to preclude spillage if the outer tank is damaged without damage to the inner tank. Some dual walled tanks are manufactured as an integral unit such that the inner and outer tanks cannot be separated, while other double walled tanks have separate inner and outer tanks nested together, yet separable from one another.

Due to the high cost of chemicals, it is important to prevent or minimize leakage from the inner tank, and if such leakage occurs, to capture the chemicals for further use without loss or contamination of the chemicals. Therefore, it is desired to provide simple, yet leak-proof seals and fittings between the tanks.

The molding process for double walled tanks is relatively complex and costly. It is also important to manufacture the tanks with maximum strength and minimal stresses. Molded plastic tanks with continuous, non-interrupted cylindrical sidewalls have greater strength and less stress points than tanks having depressions or other formations in the sidewall, which increase circumferential or hoop stress in the tank sidewall, thereby weakening the sidewall strength.

Accordingly, a primary objective of the present invention is the provision of an improved double walled storage tank assembly for agricultural and industrial liquids.

A further objective of the present invention is the provision of a liquid storage tank assembly having nested inner and outer tanks to form a dual wall construction.

Another objective of the present invention is the provision of a liquid storage tank assembly having an affective sealing gasket between inner and outer tanks.

Still another objective the present invention is the provision of a double walled liquid storage tank assembly having a compression fitting extending through both walls.

Yet another objective of the present invention is the provision of a storage tank assembly for agricultural and industrial chemicals having dual walls, with the outer wall having a recess to mate with the inner wall.

A further objective of the present invention is the provision of an improved liquid storage container which is economical to manufacture, and durable and safe in use.

These and other objectives will become apparent from the following description of the invention.

SUMMARY OF THE INVENTION

The liquid storage tank assembly of the present invention is intended for use in storing agricultural and industrial chemicals, and can be manufactured in a variety of sizes ranging from approximately 50 gallons to over 10,000 gallons. The assembly includes molded plastic inner and outer tanks which are removably nested together to form a double walled construction. The outer tank includes an upper shelf, and the inner tank includes an upper rim. A leaf gasket is mounted on one of the tanks so as to provide a seal between the shelf and the rim when the inner and outer tanks are nested together. The outer tank has a recess formed therein near the bottom of the tank. The recess is formed with a flat back wall which mates with a flat wall portion on the inner tank. A compression fitting extends through the flat wall portions of the inner and outer tanks. The compression fitting includes an inner plate on the inside of the inner tank and an outer plate on the outside of the recess of the outer tank. Gaskets are provided on both sides of the inner tank around the fitting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the double walled liquid storage tank assembly of the present invention.

FIG. 2 is an exploded view of the inner and outer tanks which form the dual wall liquid storage tank assembly of the present invention.

FIG. 3 is a sectional view through the tanks.

FIG. 4 is an exploded view of the tanks showing the sealing gasket and the compression fitting for the tanks.

FIG. 5 is a sectional view showing the inner tank nested within the outer tank and the sealing gasket therebetween.

FIG. 6 is an enlarged sectional view of the compression fitting.

FIG. 7 is a perspective view of an alternative embodiment of the tank assembly having lifting lugs on the inner and outer tanks.

FIG. 8 is a side elevation view of the assembly shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The dual tank assembly of the present invention is generally designated in the drawings by the reference numeral 10. The assembly 10 includes an inner tank 12 and an outer tank 14. Preferably, each tank is molded plastic.

The inner tank 12 has a cylindrical sidewall 16, a bottom 18, and a top cover 20, all integrally formed as a one piece unit. The top 20 of the inner tank 12 has at least one opening with a removable lid 22 for filling the tank 12. The cover 20 includes a rim 24 extending outwardly from the sidewall 16.

The outer tank 14 includes a cylindrical sidewall 26, a bottom 28, and an open top 30. The upper end of the sidewall 26 terminates in an inwardly extending shelf 32. The diameter of the sidewall 26 is greater than the diameter of the sidewall 16, such that when the inner tank 12 is nested within the outer tank 14, a space or gap 34 resides between the sidewalls 16, 26 so as to define a containment area between the tanks 12, 14.

When the inner tank 12 is set into the outer tank 14, the rim 24 of the inner tank 12 resides over the shelf 32 of the outer tank 14. A gasket 36 seals the space between the rim 24 and the shelf 32. In a preferred embodiment, the gasket 36 includes a channel 38 for mounting onto the edge of the shelf 32, as best seen in FIG. 5. A flexible leaf 40 of the gasket 36 extends upwardly and outwardly from the channel 38. Preferably, the rim 24 is sloped approximately 20° from horizontal, as seen in FIG. 5, so as to assure sealing engagement with the leaf 40 when the inner tank 12 is lowered into the outer tank 14.

Drainage of liquid from the inner tank 12 is accomplished via a compression fitting 42 extending through the sidewalls 16, 26 of the inner and outer tanks 12, 14, respectively. More particularly, the fitting 42 comprises an inner plate or ring 44 and an outer plate or ring 46. The sidewall 26 of the outer tank 14 includes a recess 48 having a flat, vertical wall 50 aligned and mating with a flat vertical wall portion 52 on the sidewall 16 of the inner tank 12. The inner ring 44 is mounted on the inside of the inner flat wall 52, while the outer ring 46 is mounted on the outside of the outer flat wall 50. The rings 44, 46 are fastened together by bolts 54 extending through holes in the flat walls 50, 52 and nuts 56. A first sealing ring 58 is provided between the inner ring 44 and the inside of the inner flat wall 52. A second gasket is sandwiched between the inner and outer flat walls 50, 52. Tightening nuts 56 onto the bolts 54 compresses the gaskets 58, 60 so as to prevent leakage from the tanks 12, 14.

The depth of the recess 48 in the outer tank 14 depends upon the volume of the tanks. For example, in a 500 gallon inner tank, the outer flat wall 50 is recessed approximately 3.26″ while the inner flat wall 52 is recessed approximately 1.26″ from the diameter of the sidewall 16 of the inner tank 12.

The inner and outer tanks 12, 14 include main drain openings 62, 64, respectively. The fitting 42 also includes a primary drain conduit 66 installed from inside the tank 12 and having a threaded outer end extending outwardly through the drain openings 62, 64 and secured by a large nut 68. A pair of ring gaskets 70 are sandwiched between the fitting 66 and the nut 68 on opposite sides of the inner flat wall 52 around the primary drain opening 62.

The main drain openings 62, 64 may have various sizes, depending upon the volume of the tank. For example, in a 500 gallon tank the opening 62 of the inner tank 12 may be approximately 3.0″, and the opening 64 on the outer tank 14 may be approximately 6.0″.

The pipe 66, nut 68 and gaskets 70 prevent leakage from the inner tank 12. The compression of the inner and outer rings 44, 46 and gaskets 58, 60 prevents leakage of liquid within the containment gap 34 from the outer tank 14. The mating flat walls 50, 52 provides for improved sealing by the gasket 60 sandwiched therebetween and compressed by the bolts 54 and nuts 56.

An auxiliary drain plug 72 is provided in the sidewall 26 of the outer tank 14 adjacent the bottom wall 26 permit to drainage any liquid collected in the containment gap 34 between the inner and outer tanks 12, 14.

FIGS. 7 and 8 show an alternative embodiment of the tank assembly 10A. The primary difference between the first tank embodiment 10 and the second tank embodiment 10A is the provision of lifting lugs or flanges on the tanks. More particularly, the inner tank 12A of the second embodiment includes a plurality of lugs or flanges 74 to lift the tank into and out of the outer tank 14A. The outer tank 14A also has a plurality of lugs or flanges 76 to lift the outer tank 14A, with or without the inner tank 12A nested therein. The inner tank 12A may be empty or full when lifted. The lugs 74, 76 are preferably molded as an integral part of the tanks 12A, 14A, respectively.

The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives. 

What is claimed is:
 1. A dual tank assembly for storing liquids, comprising: an outer tank; an inner tank nested within the outer tank; the outer tank having an upper shelf; the inner tank having a rim overlapping the shelf with a gap therebetween; and a flexible leaf gasket residing between the shelf and the rim to seal the gap.
 2. The dual tank assembly of claim 1 wherein the leaf gasket is mounted on the shelf.
 3. The dual tank assembly of claim 1 wherein the leaf gasket extends angularly in the gap.
 4. The dual tank assembly of claim 1 wherein the leaf gasket extends upwardly and outwardly from the shelf.
 5. The dual tank assembly of claim 1 wherein the inner the inner and outer tanks each have cylindrical sidewalls which are spaced apart from one another.
 6. The dual tank assembly of claim 1 wherein the outer tank has a bottom, a sidewall, and an inwardly extending upper lip, with the lip forming the shelf.
 7. The dual tank assembly of claim 6 wherein leaf gasket is mounted on the lip.
 8. The dual tank assembly of claim 1 wherein the inner tank has a bottom, a sidewall, and a top cover, with the rim extending between the top cover and the sidewall.
 9. The dual tank assembly of claim 8 wherein the rim is sloped.
 10. The dual tank assembly of claim 1 wherein the leaf gasket has a channel for mounting to the shelf.
 11. A dual tank assembly for storing liquids, comprising: an outer tank having a bottom, a sidewall, and an open top; an inner tank nested within the outer tank, and having a bottom, a sidewall, and a top cover; a containment space between the sidewalls of the tanks; a recess in the sidewall of the outer tank, the recess residing adjacent the sidewall of the inner tank; a fitting extending through the recess and through the inner tank sidewall for draining liquid from the inner tank.
 12. The dual tank assembly of claim 11 wherein the fitting includes an inner ring on the inside of the inner tank and an outer ring on the outside of the recess, the rings being fastened together.
 13. The dual tank assembly of claim 12 wherein the rings are compressed together by a plurality of fasteners.
 14. The dual tank assembly of claim 12 herein the fitting includes a gasket residing between the inner ring and the inside of the inner tank.
 15. The dual tank assembly of claim 12 wherein the fitting includes a gasket residing between the recess and the inner tank sidewall.
 16. The dual tank assembly of claim 12 wherein the fitting includes a first gasket between the inner ring and the inside of the inner tank and a second gasket between the recess and the sidewall of the inner tank.
 17. The dual tank assembly of claim 12 wherein the fitting includes a drain conduit extending through the rings.
 18. The dual tank assembly of claim 11 further comprising a drain plug in the outer tank adjacent the bottom.
 19. The dual tank assembly of claim 11 wherein the fitting is mounted on the tanks under compression so as to pull the recess and inner tank sidewall toward one another.
 20. The dual tank assembly of claim 19 wherein the compression is provided by threaded fasteners, each extending through the fitting and through the inner and outer tanks.
 21. The dual tank assembly of claim 11 wherein the recess has a planar back wall and the inner tank has a planar area on the sidewall aligned with the recess back wall, and through which the fitting extends.
 22. The dual tank assembly of claim 11 wherein the recess and the inner tank each have flat areas aligned and compressed together by the fitting. 